412 Dr. Schunck on Rubian and its Products of Decomposition, 



with cold alcohol. This dissolves the rubiretine, leaving behind 

 the greatest part of the verantine. The alcoholic liquid, after 

 filtration and evaporation, leaves a residue of rubiretine with its 

 usual appearance and properties. Should it not melt easily when 

 thrown into boiling water, it must again be treated with a small 

 quantity of cold alcohol, when an additional portion of verantine 

 remains undissolved, and the alcohol on evaporation usually gives 

 pure rubiretine. Should it, however, still contain verantine, the 

 process of treating with cold alcohol must be repeated, until it 

 is free from that substance. The alcoholic liquid filtered from 

 the lead precipitate contains the substance which 1 call rubiadine. 

 In order to obtain it in a state of purity, water is added to the 

 solution. This produces a yellow precipitate, which after filtra- 

 tion is treated with just sufficient boiling alcohol to dissolve 

 it. To the solution while boiling, there is added hydrated oxide 

 of lead, which takes up the impurity, consisting chiefly of rubi- 

 retine, and renders the solution of a lighter yellow. The liquid, 

 after being filtered boiling hot, deposits the rubiadine on cooling 

 in small yellow needles. An additional quantity may be procured 

 by evaporating the mother-liquor, but this portion is not suffi- 

 ciently pure to assume a crystalline form, and has the appearance 

 of an amorphous yellow powder. By exposing it to heat, however, 

 a crystalline sublimate of rubiadine may be obtained. 



The acid liquid filtered from the mixture of the four preceding 

 substances still contains in solution another product of decom- 

 position. After neutralizing the sulphuric acid with carbonate 

 of lead, and evaporating the filtered liquid to dryness, a residue 

 is left, which is treated with alcohol. This leaves undissolved 

 the sulphate of soda, and after filtration and evaporation gives a 

 brown glutinous mass, which has all the properties of the sugar 

 produced by the action of acids on rubian. It is this sugar, 

 which, by the continued action on it of the caustic alkali, gives 

 rise to the formation of the dark brown flocculent substance, 

 insoluble in alcohol, which is found mixed with the four pre- 

 ceding products of decomposition. This fact is sufficiently proved 

 by the composition of the latter substance, which is identical with 

 that of the brown substance produced by the action of strong 

 acids on ordinary sugar. 



The products formed by the action of caustic baryta on 

 rubian do not differ from those resulting from the action of 

 caustic soda. On adding caustic baryta to a solution of rubian 

 * and boiling for some time, the rubian is entirely decomposed ; 

 the decomposition, as might be supposed, requiring a rather 

 longer time for its completion than in the case of caustic soda. 

 After the process is finished, the products of decomposition are 

 found for the most part in combination with baryta in the shape 



